OF NORTH AMERICA. 251 



causes the aperture to be continuous ; umbilical chink round, wide and 

 deep, exhibiting one or more volutions ; the base of the shell is roundly 



flattened. 



Length. Breadth. Aperture length. Breadth. 

 8.50 3.50 3.50 2.00 mill. Type 



8.75 4.00 3.50 2.00 " 



7.60 3.50 3.00 2.00 " 



TYPES: The Chicago Academy of Sciences, four specimens, No. 

 23157; cotypes, Philadelphia Academy of Sciences, No. 89172. 



TYPE LOCALITY: Owasco Lake, New York. 



ANIMAL, JAW, RADULA and GENITALIA: Unknown. 



RANGE : New York state. A species of the Alleghanian division 

 of the Transition life zone and of the Canadian region. 



RECORDS. 



NEW YORK: Cazenovia, Madison Co. (Henderson) ; Owasco Lake, Cayuga 

 Co. (H. N. Lyon) ; Cazenovia, Madison Co., and Williamsville, Erie Co. 

 (Walker). 



GEOLOGICAL RANGE: Unknown. 



ECOLOGY: Along the shore on debris, such as sticks, reeds, etc., 

 or on stones and submerged vegetation. 



REMARKS : Owascoensis may be known by its elongated, narrow 

 spire, turreied, flat-sided whorls and large, round, open umbilical chink. 

 The whorls appear, when viewed in outline, like boxes of diminishing 

 size set one upon another. The shape of the aperture is also peculiar. 

 Its nearest ally is parva, from which it may be distinguished by its 

 flat-sided and shouldered whorls, its generally compressed outline and 

 its more open, round and deep umbilical chink which exhibits the last 

 volution. 



Galba dalli (Baker). Plate XXX, figures 13-18. 



Lymn&a parva BAKER, Nautilus, XIX, p. 52, 1905 (not of Lea). 



Lymnaa dalli BAKER, Bull. 111. State Lab. N. H., VII, p. 104, 1906; Nautilus, 

 XX, p. 125, 1907 (description). HANNA, Nautilus, XXIII, p. 96, 1909. 



SHELL: Very small, thin, ovate-conic, turreted; color greenish 

 or whitish horn; surface dull to shining, marked by heavy, crowded 

 growth lines which are elevated into indistinct ridges in some speci- 

 mens ; nucleus very small, flatly rounded, light horn-colored, similar 

 in form to that of Galba parva. Whorls 4^-5, rounded and distinctly 

 shouldered; spire generally obtusely conic, turreted, a trifle longer 

 than the aperture; sutures very deeply impressed; aperture elongate 

 ovate or elliptical, continuous in many specimens; outer lip acute; 

 inner lip forming a rather flat erect extension over the umbilical region, 

 leaving a pronounced chink; the lower part of the aperture is some- 

 what effusive; the columellar extension of the inner lip is sometimes 



